JPH03219195A - Muffling device in air duct system - Google Patents

Abstract

PURPOSE:To enable displaying a high muffling effect even in a low sound range by providing an air passage having a variable sectional area so constituted as to have expanded and contracted sectional areas with a division opposing a pair of inner surfaces of an air supply duct body. CONSTITUTION:A muffling elbow 1 has an elbow body 2 as an air supply duct body and a division 3 laid in the elbow body 2. The division 3 is housed in the elbow body 2 and so formed as to be slantly opposite to the inner wall surface 13 of the duct body 2 having surfaces 12 and 12 formed with the inner wall 9 of a set of the side parts 7, 7, and 8 of the elbow body 2. The insides of the elbow body 2 is cellularized with the division 3, and air passages 14 and 15 having a variable sectional area to expand and contract depending upon the expansion and contraction zones, are provided between the opposing sloped surfaces comprising the surface 12 of the division 3 and the inner wall surface 13. According to the aforesaid construction, it is possible to expect a muffling effect due to reflection and even a reactance effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a blower duct system such as an air conditioner or various smoke evacuation devices, and more particularly to a muffler in a blower duct system for reducing noise.

[Prior art] For example, in an air conditioner at A location, the bird noise generated by the blower is transmitted into the room through the duct system, and even in the duct system, it is transmitted through the duct, elbow, damper guide vane, etc. In addition, noise is generated, but the noise from the duct system is not as loud as the one on the left, except for special high-speed air blowing cases.

In order to muffle these noises, there are methods that line the inner walls of the duct system with sound absorbing material, methods that reflect the noise back to the sound source by interposing an elbow, and methods that utilize sound resonance. And it is used.

[Problem to be Solved by the Invention] However, although these silencing means are relatively effective in silencing mid- to high-frequency sounds, their silencing effect on low-frequency ranges is said to be significantly lower, and duct system,
For example, in the case of an elbow, assuming that the opening width is W (m) and the sound frequency is f (Hz), looking at the relationship between the value of Wxf and the amount of attenuation of sound passing through the elbow, WXf is 100m-H.
The amount of attenuation for z (100 Hz sound in an elbow with an opening width of 1 m) is about 3 db, and the attenuation amount is about 3 db at 70 to 80 m-H2 or less.
It has been pointed out that it is about db or less.

The present invention has been made in view of these problems, and an object thereof is to provide a sound damping device for a blower duct system that can exhibit a high sound damping effect in the low frequency range.

[Means for Solving the Problems 1] In accordance with the above-mentioned object, the present invention has a cross-section of the air flow passage in the air duct system, for example, by enlarging and reducing or reducing-enlarging-reducing-enlarging, etc. The present invention was completed by discovering the fact that a noise reduction effect extending to a low temperature range can be obtained by changing the structure to a partition plate, and a cross-sectional variable ventilation flow path defined by the partition plate on each side of the inner and outer peripheries and forming enlarged and contracted sections between the inclined surfaces of the surface of the partition plate and the inner wall surface. The present invention relates to a silencing device for a blower duct system, which is characterized by being equipped with the same.

[Function] By arranging the partition plate so as to face the inner wall surface of the pair of air duct system bodies at an angle, the inside of the air duct system main body is divided into a plurality of air flow passages, and these flow passages are The cross section expands and contracts with respect to the air blowing direction between the partition plate and the inner wall surface of the air duct system main body that face each other at an inclined angle. This air blowing flow path with a change in its expansion/contraction cross section itself has a blocking effect of reflecting noise including those in the low temperature range, thereby muffling the noise generated by the blower within the system.

[Embodiment] The embodiment will be further described below with reference to the drawings. What is shown in the drawings is an example in which the air duct system is an elbow, and the present invention is applied to this elbow. In FIG. 2, reference numeral 1 denotes a sound-muffling elbow, and the sound-muffling elbow 1 is configured to include an elbow main body 2, which is a main body of an air duct system, and a partition plate 3 disposed inside this elbow main body 2. It is.

The elbow main body 2 is a right-angled elbow that has openings 4.4 in two orthogonal directions to change the flow direction of air, and is made by bending a zinc iron root and joining the joints with a gap. Then top plate part 5, bottom plate f! 1+6. It is formed by providing two side plates 7.7 on the outer circumferential side perpendicular to these, and an inclined inner side plate part 8 between the openings. These top plate part 5, bottom plate part 6, and each side plate part 7, 7, 8 are provided with inner walls 9 made of punched metal spaced apart and parallel to each other, and the peripheral edges are welded or riveted. They are joined together to form a double structure, and the space between them is filled with glass wool lO for sound absorption and heat insulation. Note that the punching holes 11 of the inner walls 9 are provided over the entire surface of the inner walls. Also,
The size of the elbow main body 2 in this example is 60 CI11 for both the width W and the height H in the inner dimensions of the exit opening 4.4.

Next, the partition plate 3 is formed into a closed annular cross-sectional shape as shown in FIG. 2 by bending a punched medal made of an aluminum alloy sintered panel and welding the edges together. It has a surface 12°I2 on both sides of the front and rear sides, on which punching holes 11 are provided throughout, and the inside is similarly filled with sound-absorbing glass wool 10. Further, its overall shape is curved into a smooth substantially ridge 11a, and the surface angle changes sequentially with respect to the direction of air blowing, and in particular, the ends are oriented parallel to the direction of inflow or outflow of air. In addition, the thickness of the partition plate 3 in this example is 5C! + Toshishita.

The partition plate 3 is built into the elbow body 2, and its surface 12.1
2 is the inner wall surface 13 . . . formed by the inner walls 9 .
It is disposed so as to face the other side at an angle. However, in this example, as seen on the inner circumferential side of the central portion, there is also a portion where the surfaces 12 of these partition plates and the inner wall surface 13 of the elbow body face each other in parallel (bq in the figure). Note that the partition plate 3 is
The top plate part 5 and the bottom plate part 6 of the elbow body are connected to the upper and lower edges respectively.
It is firmly fixed to the inner wall surface 13.13 by welding and stands upright.

By arranging the partition plate 3 in this way, the inside of the elbow main body 2 is divided into inner and outer circumferential sides, and the surface 12, 12 of the partition plate 3 and the inner wall surface 13... A cross-section-changing ventilation channel 14, 15 is formed which expands and contracts according to the expansion and contraction sections.

First, to explain from the first cross-sectional variable ventilation flow channel 14 on the inner peripheral side, from the upper right in FIG. An enlarged section a, a constant section b, a reduced section C1, and a length e
It reaches the other opening 16 having a width W1 through the neck 17 of the opening. Then, the expansion-constant-contraction section (a+b+
In part c), a resonance chamber 18 having a planar area S and a volume V=SXH is formed.

In this example, w 1 = 20 cm, I2 = 20
cm, S is about 9000 cffi'', and if the sound speed C is 3.4 x 10' cm/sec, then the resonant layer 1if is f= (c/2x)xsQll (s/
(j2V)) (c/2 x) x S Q Rl
From w I / ((l S )), it is set to about 50 Hz to 60 Hz.

On the other hand, the second cross-sectional variable ventilation flow path 15 on the outer circumferential side includes, in order from the top in FIG.
Then, it reaches the other opening 19 via the reduced section d of the channel cross section - the enlarged section e - the reduced section f - the amount enlarged section g - the neck 20 of length ε, and reaches the enlarged section (3 and 3) of the channel cross section. A resonance chamber 21 is formed in the reduced section f.In addition, in this example, w
2 = 35c steel.

Note that the neck portion 17.20 of the cross-sectional variable ventilation flow path may be omitted (in that case, the resonant frequency f will be ε− in the above formula).
Set it as 〇.

Next, FIG. 3 shows another embodiment, in which the noise-reducing elbow l is larger than that of the above-mentioned embodiment, and the width W of the single person exit area is increased to 1 m. According to this, the opening of each cross-sectional variable ventilation flow path is also wl = 32 cm, w 2
= 63 cm. In addition, in both wing parts of the partition plate, the surface 1.2.12 and the wall surface 13 inside the elbow body...
- Which inclined facet ff+ degree is deeper than in the above embodiment.

The noise-reducing elbow 1 in the same (other embodiment) shown in FIG.
The widths W1 and W2 of the opening of each cross-sectional variable air flow path are the same as in the first embodiment, but the side plate portions 7.7 of the elbow body.
The length of 8 is shortened.

In addition, in the other embodiment shown in FIG. 5, by changing the thickness of the partition plate 3, its surface 12 (particularly refer to the outer circumferential surface of both wing parts) is inclined to face the inner wall surface 13 of the elbow body. This is an example in which the width W of the outflow opening and the width w1 of the opening of each cross-sectional variable ventilation channel fj. w2 is the same as the first embodiment, but differs in that the neck 17 on the lower left side of the first cross-sectional air passage 14 on the inner circumferential side is longer (Q = 50 cm) and the planar shape is asymmetrical. In addition, in this example, the planar area S of the resonance chamber 18 of the first cross-sectional change ventilation flow is approximately 77
00 cm", and as a result, the resonant frequency f is 40
It is set to about Hz.

Furthermore, in another example shown in FIG. 6, by bending the partition plate 3 into an arc shape, the angle of this surface 12, 12 is sequentially changed according to the air flow direction, and the inner part of the elbow body is This is an example in which the M 11 is made to face the wall surface 13. Here, the radius of curvature of the upper cut 3 is 80 cm on the inner surface 12, and other dimensional relationships are the same as in the first embodiment.

In addition, in each of the embodiments shown in FIG. 14, the same constant section b, the same reduced section C1, and the ?a road surface reduced sections d and f, and the same enlarged sections e and g in the outer peripheral side cross-sectional change ventilation channel 15. The meaning is the same, and other points also differ depending on the above-mentioned dimensional relationships, etc.
1 and 2 are the same as those shown in FIG. 1 and FIG. 2 except for .

Using the sound-deadening elbow shown in each of the above examples as a test specimen, a subinono was placed on one side of the exit opening 4.4, a microphone connected to a voltmeter was placed on both sides, and a wind speed of 10 to 15 m/sec was placed. As a result of measuring the silencing effect, the test sound was changed steplessly from 50 Hz to 500 Hz, and under each condition of pink noise with fixed rII numbers of 63 Hz, 125 Hz, and 250 Hz, the first f) 2 on the side of the cross-section changing ventilation flow path 14
5 db, approximately 15 db on the second cross-sectional change ventilation flow path 15 side
, an average attenuation of about 20 db was observed.

The above was done with a noise-muffling elbow in a blower duct system, but as is clear from the explanation, in the present invention, the main body of the blower duct system can be used as a duct that blows air in a straight line or as a branch from which air is diverted. This silencing device can be applied to appropriate locations in other ventilation duct systems, such as branch ducts that are used alone or in combination with elbows.

When configuring a noise-reducing duct, the partition plate may have an inclined shape that faces the pair of inner wall surfaces in the air blowing direction, that is, the longitudinal direction of the duct body. Alternately and consecutively, inverted (shaped), oblate N-shaped,
It can also be made into a W-shape or a continuous wavy shape.

Furthermore, in carrying out the present invention, the material and structure of the partition plate can be freely selected; for example, it may be made of a single plate without punching, or the material may be changed to several pieces or a single glass wool plate, etc. Alternatively, it is also possible to arrange a plurality of partition plates to form three or more cross-section-changing ventilation channels in the ventilation duct system. The partition plate does not necessarily need to be installed over the entire length between the ventilation openings of the duct body (for example, it may be installed from a position slightly inside from the opening, or In the relationship between and the partition plate,
Instead of arranging the above-mentioned partition plates upright in the vertical direction, they may be arranged horizontally in a recumbent manner. Note that the ventilation duct system to which the present invention can also be applied Diameter 30
There is no particular restriction on the scope of application, from small ones of 1.5 m or less to large ones of 1.5 m or more, and there is no need to limit the type. Naturally, the present invention can also be applied to elbows of curved pipes.

As is clear from the above, in carrying out the present invention, the specific shapes and structures of the main body of the air duct system, the pair of inner wall surfaces, the partition plate, the cross-sectional variable air flow path, the expansion/contraction section of the cross section, etc.
Dimensions, materials, number of members, arrangement, additional installation of inner walls, etc. may be variously changed as long as they do not go against the gist of the invention, and are not limited to what has been illustrated or explained in the book.

[Effects of the Invention] Since the present invention is constructed as described above, the cross-sectional variable ventilation flow path in which the cross-sectional expansion/contraction section is formed has a reactance effect in addition to the silencing effect due to the anti-q1 action, and the low-temperature It is possible to achieve advanced effects over a wide range of sounds, including

In addition, the two-position l/l sound of the present invention has a simple structure in which the partition plate is disposed on the inner wall surface of the main body of the air duct system in an inclined manner, so it is relatively easy to produce. The plate is built into the main body of the air duct system and does not require any extra space outside of it, so it is not bulky and does not interfere with piping.

Furthermore, although the partition plate installed in the main body of the ventilation duct system divides the ventilation flow path into multiple sections, it can prevent the overall cross-sectional area of the flow path from being significantly reduced, thereby simultaneously suppressing an increase in flow resistance. is also possible.

[Brief explanation of drawings]

The drawings show an embodiment, and FIG. 1 is a partially cutaway perspective view of a noise-reducing elbow in an example in which the main body of the air duct system of the present invention is an elbow, FIG. 2 is a cross-sectional view thereof, and FIGS. 3 to 6 2A and 2B are cross-sectional views of the same muffling elbow showing other embodiments, respectively. 1... Silent elbow 3... Partition root 2...
Elbow body 4...Popular opening 12...Surface of partition plate 13...Inner wall surface 14.15...Changed cross-section ventilation channels a, e, g...Expanded section c of cross-section, d, f...Reduced section of cross section

Claims (1)

[Claims] A partition plate arranged to face a pair of inner wall surfaces of the air duct system body at an angle, and partitioned into inner and outer circumferential sides by the partition plate, and a surface of the partition plate and the inner wall face at an inclined angle. A noise muffling device for a blower duct system, characterized by comprising a cross-sectional variable blower flow path having enlarged and reduced cross-sectional sections formed therebetween.